Non-invasive transcranial magnetic stimulation (TMS) of the human cerebral cortex, particularly the motor areas, has now been
developed to the stage at which it is possible to evaluate in vivo glutamatergic, cholinergic and GABAergic circuits of the
human brain.1 In addition, repetitive stimulation with TMS produces long-lasting changes in the excitability of central motor circuits
that are thought to be caused by early stages of synaptic long-term potentiation/depression, thus providing for the first
time the opportunity to explore plasticity in the conscious human brain.2,3 The TMS paradigm termed short latency afferent inhibition (SAI), based on coupling peripheral nerve stimulation with cortical
TMS, provides information on central cholinergic circuits: SAI is abolished …